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Table of Contents United States Securities and Exchange Commission Washington , D.C. 20549 FORM 10 - K Annual Report Pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 Securities registered pursuant to Section 12 ( b ) of the Act : Title of Each Class Common Stock , $ 0.01 par value X ( Mark one ) Delaware ( State or other jurisdiction of incorporation or organization ) for the fiscal year ended December 26 , 2020 Or Transition Report Pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 for the transition period from to Commission file number 0-20388 LITTELFUSE , INC . ( Exact name of registrant as specified in its charter ) Trading Symbol LFUS 8755 West Higgins Road Suite 500 Chicago , Illinois 60631 ( Address of principal executive offices ) 36-3795742 ( I.R.S. Employer Identification No. ) 773-628-1000 ( Registrant's telephone number , including area code ) Name of Each Exchange On Which Registered NASDAQ Global Select Market SM Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes > No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Yes No Indicate by check mark whether the registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes No Indicate by check mark whether the registrant has submitted electronically , every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S - T ( Section 232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit and post such files ) . Yes > No Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or emerging growth company . See the definitions of " large accelerated filer , " " accelerated filer , " " small reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act : Large accelerated filer Accelerated filer Non - accelerated filer Smaller reporting company Emerging growth company If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13 ( a ) of the Exchange Act . □ L Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No The aggregate market value of 24,339,778 shares of voting stock held by non - affiliates of the registrant was approximately $ 3,956,326,119 based on the last reported sale price of the registrant's Common Stock as reported on the NASDAQ Global Select MarketSM on June 27 , 2020 . As of February 12 , 2021 , the registrant had outstanding 24,537,415 shares of Common Stock , net of Treasury Shares . DOCUMENTS INCORPORATED BY REFERENCE Portions of the Littelfuse , Inc. Proxy Statement for the 2021 Annual Meeting of Stockholders ( the " Proxy Statement " ) are incorporated by reference into Part III of this Form 10 - K .